AN ABSTRACT OF THE THESIS OF
for the
WEN-YUH LEE
(Name)
in
OCEANOGRAPHY
MASTER OF SCIENCE
(Degree)
presented on
30 November 1970
(Major)
(Date)
Title: THE COPEPOES IN A COLLECTION FROM THE SOUTHERN
COAST OF OREGON, 1963
Abstract approved:
Redacted for Privacy
Plankton samples for this present study were collected from an
area off the southern Oregon coast, extending westward to about 83
kilometers offshore. Over this sampling area, 41 species of adult
copepods were identified, including representatives of 26 genera and
17 families. The total abundance averaged 5501m 3
Population densities of copepods as a group were found higher
inshore than offshore and this distribution was largely determined by
four dominant species, that is, Oithona similis, Pseudocalanus
minutus, Acartia longiremis, andAcartia clausi. They accounted
for approximately 81% of the total copepod abundance.
Species diversity had a tendency to increase with distance
from the coast. This could be due to the possibilities that the
sampling depth was increased offshore, or that the living environment
was more stable offshore than inshore.
Rank-correlation analysis of the four dominant species, fish
eggs, copepod nauplii, euphausiids, and Eucalanus bungii suggest
that the positively correlated category includes several pairs, Oithona
similis to Pseudocalanus minutus, 0. sirnilis to Acartia clausi, A.
longiremis to P. minutus, fish eggs to 0. similis, A. longiremis to
A. clausi, 0. similis to copepod nauplii, and fish eggs to copepod
nauplii.
The negatively correlated category includes three pairs,
euphausiids to copepod nauplii, euphausiids to fish eggs, and
euphaus lids to 0. similis.
Results from the correlation analysis of the dominant species
relative to temperature, salinity, and distance from shore show that
no significant relationshipwas apparent except that the occurrence of
P. minutus was negatively correlated to distance from shore.
The Copepods in a Collection from the
Southern Coast of Oregon, 1963
by
Wen-Yuh Lee
A THESIS
submitted to
Oregon State University
in partial fulfillment of
the requirements for the
degree of
Master of Science
June 1971
APPROVED
Redacted for Privacy
Profeshor of Oceanography
in charge of major
( /
Redacted for Privacy
Chairmn of Departmen4 of Oceanography
Redacted for Privacy
Dean of Graduate School
Date thesis is presented
Typed by Mary Jo Stratton for
Wen-Yuh Le
ACKNOWLE DGEMENT
I wish to thank Dr. James E. McCauley and Dr. Charles B.
Miller for their patient guidance, for encouragement, and for reviewing
this manuscript. I thank Dr. William 0. Pearcy for his valuable
suggestions and for providing the research materials. Thanks are
also extended to Dr. Victor T. Neal, Gerard A. Bertrand, and Harry
R. Tyler for their assistance and warm friendship during the last
two years.
I also wish to thank my wife, Ying-j, for her encouragement
and understanding throughout this study.
TABLE OF CONTENTS
Page
INTRODUCTION
1
Objectives
i
Review of Literature
3
MATERIALS AND METHODS
RESULTS
Spatial Distribution of Copepods
Zooplankton Composition
Total Abundance of Copepods
Some Important Species and Their
Distribution
Miscellaneous
Patterns of Species Diversity
Correlation Analysis of Dominant Species
7
11
11
11
11
20
29
29
35
DISCUSSION
45
SUMMARY
47
BIBLIOGRAPHY
50
APPENDICES
Appendix 1
Appendix 2
Appendix 3
Appendix 4
Appendix 5
53
54
55
61
62
LIST OF FIGURES
Page
Figure
1
Station locations for MODOC
cruise, 1963.
2
Total abundance of copepod in
relation to the six sampling lines.
3
4
5
6
7
8
9
17
Abundance of Oithona similis
in relation to the six sampling lines.
23
Abundance of Pseudocalanus minutus
in relation to the six sampling lines.
25
Abundance of Acartia clausi in
relation to the six sampling lines.
27
Abundance of Acartia longiremis in
relation to the six sampling lines.
30
Species diversity of copepod.
population in relation to the six
sampling lines.
33
Correlation of species between
category-2 and category-3.
41
LIST OF TABLES
Page
Table
1
2
3
4
5
6
7
8
9
10
Sampling stations, MODOC cruise,
i6-2O August, 1963.
8
Families, genera, and species of
copepods and some other zooplankton
in the samples.
12
Total abundance, percentage of
copepods, number of species and
volume of water filtered at each
station.
16
Ranking of 25 sampling stations,
based on the abundance of each of
the eight organisms.
37
The rank- correlation coefficients
between each pairing of the eight
organisms.
38
Category-2, which shows positive correlation and has a value of r5 greater
than 0. 396.
39
Category-3, negatively correlated
group, having the conditions for
less than -0. 396.
39
List of species which comprised
category-2 and category-3.
41
Ranking of 25 sampling stations by
the total abundance of copepod,
percentage of copepod, temperature,
salinity, and distance from shore.
43
The rank-correlation coefficients of
these four dominant species, total
abundance of copepod and percentage
of copepod relative to temperature,
salinity and distance from shore.
44
THE COPEPODS IN A COLLECTION FROM THE
SOUTHERN COAST OF OREGON, 1963
INTRODUCTION
Objectives
Copepods, belonging to the class of Crustacea, are one of the
most important links in a marine pyramid. They are very common
in comparison to other plankton groups in the sea (Ackefors, 1965).
In the old time they were known as sea-insects. Elton (1927) called
copepods the key-industry animals, because they convert the energy
produced by diatoms into animal substance. As it is well known, the
copepods have long been considered to be an important food item for
some commercial fishes; for example, Calanus finmarchicus and
Calanus tonsa are the principal food for herring. Near the coast, it
seems that where the Calanus are, the herring are almost sure to
follow (Berrill, 1966). According to Lebour's (1918) study of the
food of post-larval fish at Plymouth, Pseudocalanus minutus, Acarti.a
clausi, Temora longiremis and Calanus finmarchicus were the four
most common species of copepods eaten by the greater number of fish.
Thus it is obvious that copepods not only provide food for fish but often
serve as an indicator to the best fishing grounds (Marukawa, 1933).
The abundance and distribution may also exert an important influence
on the fishery, such as modifying the migration of fish or causing the
2
decreases or increases in the quantity of fish caught (Clarke, 1934).
In a given copepod population, it appears that not all species are
equally successful. The dominants in the population are represented
by large numbers or large biomass. Odum (1963) pointed out that a
few dominant species may exert a major controlling influence in the
nature of a population by virtue of their numbers, distributional
patterns, and activities. These dominant species may modify the
environment in various ways for other species (Whittaker, 1965). A
correlation analysis among dominant species shows if they tend to
occur together or if they occur in opposite directions. As to the
number of species, it is usually lower where the conditions of
existence are unstable or severe (Odum, 1963). Therefore, the
number of species in a population often shows the degree of stability
of their living environment and the characteristics of dominant
species.
Along the Oregon coast, the copepod population has been invest
igated since 1949, but observations off the southern Oregon coast
are still far from complete. The purposes of this study are to 1)
identify the dominant species, 2) search for correlations among the
dominant species, 3) describe their horizontal distribution, 4) learn
how species diversity is related to the distance from the coast and to
some of the hydrographical features of these waters, and 5) compare
the results to those from other areas, like the region off Newport.
3
Review of Literature
The earliest reference to the copepods of Oregon coastal water
is that of Davis
(1949),
who reported
63
species in collections extend-
ing from San Francisco Bay on the south to the Aleutian Island on the
north, including the inland waterways of the coasts of Washington and
British Columbia. Frolander
(1962)
described the quantitative estima-
tion of zooplankton off the coasts of Washington and British Columbia.
In his plankton samples, Pseudocalanus minutus and Oithona similis
were the most numerous zooplankters. Species of cyclopoid copepods
occurring in the coastal waters of Oregon, California, and lower
California were listed by Olson
(1963).
albacore oceanography survey, Owen
In the northeast Pacific
(1963)
listed twenty-six species
of copepod, of which Eucalanus bungii californicus, Calanus fin-
marchicus and Microc4lanus sp. were the most common species.
These species were different from those found by Frolander
and Cross
(1964);
(1962)
possibly due to the variation of station locations and
of sampling season.
Several theses from Oregon State University deal with copepods
from Oregon coastal waters. The seasonal and geographical
distribution of pelagic species has been investigated by Cross
(1964).
He reported that Pseudocalanus minutus, Oithona similis, Acartia
longiremis, Acartia danae and Centropages abdominalis (
C.
4
mcmurrichi)1 were the most significant species off Brookings.
The
last two species were described as possible indicators of seasonal
hydrographic change because they were not present at all times of the
year. This was also noted by Frolander (1962) and Hebard (1966).
During the summer time, from July through September, a southerly
current was developed and A. danae was absent within 105 kilo-
meters (65 miles) from the Oregon coast, while in the winter time
the reappearance of A. danae was accompanied by the presence of the
northerly flow of the Davidson currrit. The reverse was true of C.
abdominalis, which occurred only from April to September. Since
the periodic occurrence of A. danae and C. abdominalis appeared to
correlate closely with the north-south seasonal changes of coastal
water flow, Frolander (1962) considered A. danae as a species indica-
tive of intrusion of near surface water from the south, Cross (1964)
suggested that both species may be used as reciprocal indicators of
seasonal change in surface current off Oregon.
Distribution of copepods in relation to oceanographic conditions
were studied by Hebard (1966), who found 67 species of copepod from
four stations off Newport, Oregon. Results from Hebard's association analysis of copepods and euphausiids revealed that Calanus
Although frequently called Centropages mcmurrichi Willey, 1920,
this species was described by Sato (1913) under the name Centropages abdominalis. This xame is used by Mon (1937).
5
finmarchicus and Calanus pacificus were the most closely associated
group and the more loosely associated groups contained the copepods
uca1anus bungii, Pareuchaeta japonica, Pleuromamma xiphias,
Gaidius pungens, and Euchirella pulchra, and the euphausiid,
Nematoscelis difficilis,
Coastal upwelling and the ecology of lower trophic levels, such
as copepods and euphausiids were described by Laurs (1967) off
southern Oregon. For convenience, he divided the hydrographic
conditions of Oregon coastal waters into four periods, that is,
pre...
upwelling, early upwelling, active upwelling and late upwelling. Active
upwelling occurred from April to July, late upwelling from August
to October. During the period of active upwelling, the isopleths of
temperature, salinity, oxygen and phosphate were tilted sharply
upward. In the late upwelling stages, all of these isopleths tend to
flatten out near the surface. However, the distribution of temperature and salinity at the late upwelling stage indicated that upwelling
was well developed north of latitude 4Z°3O, but less developed to the
south, including the C, D, E, and F sampling lines of this study.
Laurs (1967) also collected my samples and provided the
hydrographic data (Appendix 5). He reported that the near-surface
water observed from the U, S. Coast Guard Cutter MODOC 16-20
August 1963 was about 1 to 4 C colder inshore than offshore.
The 10
C isotherm lay near the shore, while at the longitude of 125°15', the
temperature increased to 12- 14 C. The salinity of surface water was
higher inshore than offshore, showing a difference of only 0. 6 %,
Laurs also reported that the standing stocks of trophic level 1 were
also considerably higher inshore than they were offshore. However,
he found the seasonal variation in the standing stock of phytoplankton
at individual stations was large but that the differences between
stations in the mean stocks were small.
7
MATERIALS AND METHODS
The materials for the present study were taken from about a
6, 800 square kilometer area off the southern Oregon coast, extending
from Cape Blanco south to the Oregon-California border and from the
Oregon coastline westward about 83 kilometers to approximately
1250 13.6'W (as shown in Table 1), These samples were collected by
Dr. R. M. Laurs on a cruise of United States Coast Guard Cutter
MODOC, August 16-20, 1963. In this square-like area, 25 samples
were collected along six sampling lines, line A to F (Figure 1).
Usually, five collections were made on each line and vertical hauls
were taken from 270 meters to the surface, except in the shallower
near-shore region. Hauls were taken with a one-half meter net
(entrance 0. 196 meter square) with 0. 239 mm mesh.
The plankton
samples were preserved immediately in the field with ten percent
buffered sea-water formalin.
In the laboratory, the larger forms such as fish larvae,
amphipods, medusae, and chaetognaths were removed first. The
larger copepods, such as Calanus finmarchicus, Eucalanus bungii,
and Euchaetajaponica were also sorted out except when they were
very numerous. Thei, the rest of the sample was subdivided five or
six times with a Folsom Plankton Splitter.
The sub-samples were
examined under the binocular microscope. The adult copepods were
Table 1. Sampling stations, MODOC cruise, 16-20 August, 1963.
Station
Wire out
Date
Time
Latitude
no.
(M)
A-i
A-2
A-4
B-2
B-3
B-4
B-5
16 Aug.
I'
1
17 Aug.
D-i
D-2
D-3
D-4
D-5
1435- 1450
H
1120-1140
08131910-1915
2132-2147
033 1-0344
1003-1005
0842-0845
0620-0634
0320-0332
0016-0027
H
1
18 Aug.
19 Aug.
1
E- 1
E-2
E-3
E-4
E-5
F-i
F-2
F-3
F-4
F-5
1815-1825
23 11-2320
1700-
U
C-i
C-2
C-4
1625- 1630
1202- 1205
1
H
20 Aug.
I'
I!
H
1345-1355
1558-1611
1838- 1847
2054-2104
1848-1851
1617-1625
1146- 1202
0848-0857
0550-0600
40
178
270
75
270
270
270
50
270
270
50
80
270
270
270
50
140
270
270
270
35
140
270
270
270
42
42
42
42
42
42
42
42
42
42
42
42
42
42
42
42
42
42
42
42
41
41
41
41
41
49. 8N
49. 6
47.8
39. 6
39.7
39.7
39. 0
29.9
29.6
29. 9
19.6
20, 1
19.9
19.9
20.5
09. 9
10.0
09.9
09.4
09. 9
59.0
59. 1
59.2
59.4
59.7
Longitude
124
124
125
124
124
124
124
124
124
125
124
124
124
124
125
124
124
124
124
125
124
124
124
124
124
39. 6W
48.0
16. 1
33, 3
46. 0
58.5
14.0
32.2
46.2
15.0
28.5
32. 8
455
58.2
12.3
24. 4
33.1
46.0
59.8
12. 9
19.5
32. 1
45.6
59.4
13.6
o
o0
o
0
0
-
0
I
I
/Cape
A-2
A-4
A-i
B1anco
\..
10
5
0
Nautical
miles
B-S
B-4
C-4
B-3
C-Z
B2
C-i
N
/
Rogue
42 030
River
Cape
D-5
E-5
D-4
E-4
D-3
E-3
Sebastian
D-2 D-i:
E-Z
E-1'
Brooking
F-5
F-4
F-3
F-2
F-i
Figure 1. Station locations for MODOC cruise, 1963.
42000
I
10
identified to species. The other zooplankton, including copepodites,
were identified to genera only, or even to family or class.
The books used for copepod identification were by Brodskii
(1967), Davis (1949), Grice (1961), Hardy (1965), Mon (1937),
Newell (1963), Park (1968), Rose (1933) and Jespersen and Russell
(1960).
The abundance of copepods is usually expressed as either number
per cubic meter or number below one square meter of sea surface.
The former is used in this study. No flow meter was used in making
the MODOC-63 hauls. Since they were vertical tows, the amount of
water filtered can be estimated by the following steps:
1) Assume the filtration efficiency of the plankton net was
100 percent.
2) Then, Volume of water filtered = (Depth of haul) x (Mouth
area of net = 0. 196 m2) x 1. 0 (= filtration efficiency).
The number of copepods per cubic meter is then calculated from
the formula: no./m3 = [subsample count x 2(no. of splits)1
/1 of
water filtered. After all calculations were made, the abundance of
copepods was expressed by the number of organisms per cubic meter
(Appendix 3).
11
RESULTS
Spatial Distribution of Copepods
Zooplankton Composition
In this study the zooplankton composition was divided into seven
categories: copepods, copepodites, cladocerans, other crustacea,
other larvae, amphipods, and other plankton (see Table 2). Copepod
population contributed 85 percent of the total number. Forty-one
species of adult copepods were identified, representing 26 genera and
17 families. All were typically marine species (see Appendix 3).
Because of their small size and incompletely developed append-
ages no attempt was made to identify the small copepodites or to count
them.
Other groups represented in the samples included cladocerans,
polychaete larvae, fish eggs, oikopleurans, and cephalopods, of
which fish eggs contributed significantly to the total number of zoo-
plankters at stations of B-4, E-4, F-4, and F-5. Whether or not
their distribution and occurrence was correlated with the abundance of
copepods needs further investigation. There were only two species
of Cladocera, Podon leuckarti and Evadne nordmanni.
Their occur-
rence was sporadic and their numbers low.
Total Abundance of Copepods
Over the sampling area, the copepod population was very high
12
Table 2. Families, genera, and species of copepods and some other
zooplankton in the samples.
Family
Species
Genus
COPE PODS
Calanidae
Calanus
C. finmarchicus (Gunner)
C. pacificus Brodsky
C. cristatus KrØyer
Eucalanidae
Eucalanus
E. btingii Giesbrecht
E. elongatus hyalinus Giesbrecht
Rhincalanus
Ps eudocalanidae Claus ocalanus
Pseudocalanus
Aetideidae
Aetideus
Gaidius
Euchirellinae
Euchirella
Chirundina
Undeuchaeta
Euchaeta
Euchaetidae
Phaennidae
Phaenna
Scolecithricidae Scottocalanus
Lophothrix
Scaphocalanus
Metridia
Metridiidae
Pleuromamma
Centropages
Centropagidae
Lucicutia
Lucicutiidae
(Continued on next page)
R. naustus Giesbrecht
C. arcuic ornis (Dana)
P. minutus (Krøyer)
armatus (Boeck)
G. brevispinus (Sars)
G. tenuispinus (Sars)
C. pungens Giesbrecht
E. pulchra (Lubbock)
E. curticauda Giesbrecht
A.
C.
U.
U.
streetsi Giesbrecht
major Giesbrecht
plumosa (Lubbock)
E. japonica (Marukawa)
P. spinifera Claus
persecans (Giesbrecht)
L. frontalis Giesbrecht
S. brevicornis Sars
M, lucens Boeck
S.
abdominalis (Lubbock)
xiphias (Giesbrecht)
guadrungulata (Dahi)
scutullata Brodsky
C. abdominalis Willey
L. flavicornis (Claus)
P.
P.
P.
P.
13
Table 2. (Continued)
Family
Genus
Heterorhabdidae
Heterorhabdus
Heterostylites
Candaciidae
Can da cia
Pontellidae
Acartiidae
Labidocera
Acartia
Species
H. tanneri (Giesbrecht)
H. longicornis (Giesbrecht)
H. major (Dahl)
C. columbiae Campbell
C. bipinnata Giesbrecht
L. amphitrites (McMurrich)
A. clausi Giesbrecht
A. tons a Dana
A. longiremis (Lilljeborg)
Oithoni dae
Oithona
Oncaeidae
Corycaeidae
Oncae a
0. similis Claus
0. spinirostris Claus
0. conifera Giesbrecht
Corycaeus
Corycaeus sp.
COPE PODITES
Calanus
Eucalanus
Ps eud,ocalanus
Aetideus
Gaidius
rjuLid.e d.
Lophothr ix
Metridia
Pleur omamma
Lucicutia
Heterorhabdus
Acartia
Oithona
Scottocalanus
C LA DOCERANS
Podon leuckarti Sars
Evadne nor dmanni Loven
OTHER CRUSTACEANS
Copepod nauplius
Barnacle nauplius
Conchoecia sp.
(Continued on next page)
Euphausiid
Cyprius
14
Table 2. (Continued)
OTHER LARVAE
Decapod larva
Polychaeta larva
Gastropoda larva
Euphausiid larva
Fish larva
AM FHIPODS
Prirnno abyssalis
Phronima s edentaria
Parathemisto sp.
OTHER PLANKTON
Doliolurn
Medusa
Fish egg
Radiolarian spp.
Tryphana sp.
Streets ia s p.
Cephalopod
Chaetognath
Oikopleura sp.
15
compared to the other six groups, ranging from 87/rn3 to 1626/rn3
with a mean abundance of 550/rn3 for these 25 observations during midAugust. Copepod abundance was found not to be positively related to
its percentage in total zooplankton. For example, the highest density
of copepods in the samplewas 1626/rn3, which occurred at station
F-i, where it composed about 72 percent of all zooplankton. While at
station C-2, the abundance was 372.4/rn3, approximately 0.23 times
that found in station F-i. Yet it represented over 98 percent of the
entire zooplankton (see Table 3).
Figure 2 shows the relationship of total abundance of copepods
to distance from the coast. No strong or consistent relationship is
apparent. Nevertheless, it is possible to generalize to some degree
and in the six sampling lines (from A to F) as a whole, two peaks
occurred, one with an average number of 1311/rn3 was found nearest
the coast, about 5. 5 kilometers offshore, and the other was observed
along the longitude of 125°00'W, with the average concentration of
603/rn3. The patterns of fluctuation along D, E, and F lines were
similar to the extent that the abundance decreased first, then reached
a secondary maximum. On the B line, the density increased seaward
and the maximum abundance occurred at the farthest station B-5.
The
pattern of C line was the reverse of B line. On the A line, the greatest
abundance was at the intermediate distance from the coast, approxirnately 21 kilometers off Cape Blanco.
Table 3, Total abundance, percentage of copepods, number of species and volume of water filtered
at each station.
Station
no.
Total
abundance of
zooplankton
(no. /m 3
)
A-i
A-2
A-4
B-2
B-3
B-4
B-5
C-i
C-2
C-4
D-1
D-2
D-3
D-4
D-5
E-1
E-2
E-3
E-4
E-5
F-i
F-2
F-3
F-4
F-5
390. 1
485. 7
155.5
335.6
399.9
461.5
1416.7
865.9
378.8
465.8
1452.2
223.3
500.8
561.4
340.5
2068.8
407.1
453.7
1016.3
461.7
2260. 3
300.0
348.6
838.7
619.4
Total
abundance
of copepods
(no. /m3
332.7
Percentage
of copepods
Volume
Number
of species
(/0)
)
85.3
7.8
93. 9
14
56.2
24
93. 9
1361.0
630.2
372.4
96. 1
8
16
12
18
5
368. 1
948.2
198.3
418.2
490.2
307. 1
1360.4
373.8
325,5
852. 1
430.5
1626.8
259.7
261.8
656.2
526.3
(m 3
34. 9
52. 9
87.4
315.2
388.9
411.7
72.8
98.3
79.0
65.3
89.2
83.5
87.3
90.2
65.8
91.8
71,7
83.8
93.2
72.0
86.6
75.1
78.2
85.0
filtered
5
456. 2
97.2
89.2
of water
13
25
11
9
14.7
52.9
52.9
52.9
9.8
52.9
52. 9
9.8
15.7
21
22
52.9
52.9
18
52. 9
6
9.8
27.4
52.9
52.9
52.9
11
18
15
21
7
6. 9
14
10
11
27.4
52,9
52.9
21
s2.9
C"
Figure 2. Total abundance of copepod in relation to
the six sampling lines. Vertical arrows extend
between confidence limits taken to be one-half
to double the sample abundance estimate.
17
0001
800
400
2400
2000
1600
1200
800
400
B5
B4
D2
I
1200
800
400
c
0
10
C2
C1
C
2000
20
Nautical mile
i600
1200
00
400
D5
D2D1
Offshore
D
125°O0'
I
I
124Q0'
2800
2400
2000
1600
1200
800
400
E
J.2
'1
3200
2800
2400
2000
i600
1200
800
400
F
F5
F4
F3
Offshore
19
Copepod abundance increased from north to south, although
relatively high mean catches appeared on the B line stations.
Off
BrooKings, the average aoundance reached 662/rn3, which showed
little difference from that found in mid-August of 1962 by Cross (1964),
who found 800/rn3.
This was possibly related to some random varia-
tion between times of sampling, or to changes of environmental
factors in different years.
As it will be seen later, the distribution of total abundance of
copepods in this study is largely determined by the two most dominant
species, Oithona similis and Pseudocalanus minutus. These two
species dominated numerically the entire copepod population and
particularly were found in most abundance near the coast (see
Appendix 1).
Brodskii (1950) has noted that P. minutus is characteris-
tic of the neritic and northern cold water. Mon (1937) considered 0.
sirnilis to be a species which was widely distributed in the water of the
world and adapted to a somewhat low temperature.
In
the period of
16-20 August 1963, the near surface water temperature was 1 to
4 C warmer offshore than inshore. This perhaps is attributable to
the coastal upwelling which lowers the surface temperature. The
mean standing stock of chlorophyll "a" observed at the inshore stations
was approximately 1. 3 to 1. 8 times higher than the mean value found
at offshore stations (Laurs, 1967).
Thus the profusion of copepod
population at the inshore stations may be due to the combined effects of
1) distributional characteristics of dominant species, 2) lower inshore
surface water temperature, and 3) higher inshore chlorophyll
HaIt.
On the B line, the highest abundance appearing at the offshore
station B-5 may be due to the nonrandom spatial distribution of copepods, since zooplankton patchiness can be an important component of
zooplankton sampling error (Wiebe and Holland, l968)
Wiebe and Holland (1968) summarized field estimates of the total
sampling error from 13 studies and found that the 95 percent confidence
limits usually exceed half or double the observed value regardless of
the type of net, the method used in towing, or the organisms used in
calculations. If one-half and double field variability limits are
considered to apply in the present study (see graphical presentation
of confidence limits in Figure 2), field error makes the abundance
of copepod at station B-4 and B-S hardly distinguishable. It seems
that the secondary maximum of D, E, and F lines found at the longitude of about 125°OO'W, may also be sampling artifacts. However,
despite the use of field error estimates, the abundance at station D- 1,
E-1, and F-1 was higher than the next stations offshore,
Some Important Species and Their Distribution
In the present study, the most important species among the
forty-one species identified were Oithona similis, Pseudocalanus
minutus, Acartia clausi, and A. longiremis. These four species
21
dominated the entire population of copepods over the 25 sampling
stations, where they accounted for approximately 81 percent of the
total copepod abundance (see Appendix 1).
One species, Ceritropages
abdominalis, is thought to be associated with changes of hydrographic
conditions (Cross, 1964; Hebard, 1966), although its exact role in the
Oregon coastal waters remains uncertain. This species was recorded
only in three samples of my collection, B-3, B-4 and D.-2, and their
number was low, not more than 5/rn3. Cameron (1957) reported that
Aetideus armaratus, Oitliona spinirostris, and Eucalanus bungii were
associated with subsurface forms. The last species was previously
recorded only from the northern Pacific and the adjacent Arctic near
Japan (Davis, 1949). In my study, its occurrence was frequent but
in low numbers (see Appendix 2).
Oithona similis. Information on abundance and seasonal fluctua-
tion of Oithona similis has been reported by Cross (1964), but his
survey was largely confined to the regions off Astoria, Newport, Coos
Bay, and Brookings, and the plankton collections were made only
during June and late July. Hebard (1966), in his study off Newport,
did not report this species. His plankton data were collected between
May, 1963 and July, 1964.
In the present study, 0. similis was the most abundant species
from the 25 stations, comprising about 35. 3 percent of the total copepod population. Comparison of distribution of 0. similis and the total
zz
copepod population revealed several similarities in the change of
abundance with distance off the coast. Along the D, E, and F lines
(Figure 3), 0. similis had one peak on the stations of D-3, E-4, and
F-4 and generally low numbers offshore. An offshore station B-5
showed maximum number of 715/m3. This was opposite to the
distributional patterns of other five sampling lines. As already mentioned, it might be due to local variation of sampling.
Pseudocalanus minutus.
This species was found both in the open
ocean and near shore. In the present study, it made up 34. 5 percent
of the copepod population, and is probably not significantly less than 0.
similis. Pseudocalanus minutus was found at all stations. Its variation of abundance (Figure 4) with the distance off the shore was closely
parallel to that of 0. similis, although some discrepancies existed.
A major distinction between these two species was that the secondary
maximum, which occurred in the D, E, and F lines for 0 similis was
almost absent for P. minutus. As a whole, this species followed a
decreasing trend in abundance at offshore stations, confirming
earlier work by Cross (1964) in Oregon coastal waters.
Acartia clausi. This species was the third most important
species (Figure 5). Although its abundance was great inshore, it did
not contribute greatly to the total copepod population. The average
percentage was 5. 7 percent, just a little higher than that of A.
longiremis. Its abundance varied among stations, in general, the
Figure 3. Abundance of Oithona similis in relation
to the six sampling lines. Vertical
arrows extend between confidence limits
taken to be one-half to double the sample
abundance estimate.
23
l2AOO'
200
100
A,
A
A1
.400
LZ00
1000
800
600
400
200
200
100
C
0
10
600
20
Nautical miles
400
200
D3
D2131
Offshore
24
124°00'
12500l
400
200
E
-)
1000
800
600
400
200
F
F5
F4
Offshore
Figure 4. Abundance of Pseudocalanus minutus
in relation to the six sampling lines.
Vertical arrows extend between
confidence limits taken to be onehalf to double the sample abundance
estimate.
25
OOO
400
1
114
200
1
I,'
400
200
B4
400
200
C2
Cl
C
800
0
10
20
600
Nautical miles
400
- 200
D4
D3
D2D1
Qffshore
26
124°00'
125°OO'
I
I
I
I
I
I
1500
1000
500
E
_5
_4
1
2000
1500
1000
500
F5
F4
F3
F2
Offshore
F1
F
Figure 5. Abundance of Acartla clausi in
relation to the six sampling lines.
Vertical arrows extend between
confidence limits taken to be onehalf to double the sample abundance
estimate.
27
000I
50
25
A
A
A
A1
200
150
100
50
B5
B4
B3
B
B2
50
25
C4
C2
C
C1
350
300
250
200
150
100
50
'
I
Offshore
1I
I
I
125O0'
,
I
I
I
.i- 300
5O
oo
150
100
50
300
250
200
150
100
50
F
4
Offshore
highest abundance occurred adjacent to the coast, with the average
concentration of 84. 2/rn3, then decreased progressively offshore.
Again, the reverse trend was noted along stations of line B.
Acartia longiremis. Although Brodskii (1950) noted that this
species is more limited and northern in distribution than A. clausi, it
was widespread for the area of this study. It occurred at all stations,
but its distribution (Figure 6) varied greatly among the six sampling
lines.
The average percentage of A. longiremis was five percent.
Miscellaneous
Copepod nauplii (Appendix 2) averaged 59/rn3. They were
frequently found in higher abundance at offshore stations. Fish eggs
occurred in high abundance at offshore stations, such as B-4, B-5,
E-4, and F-4. If these were considered as members of the zooplankton, they would contribute significantly to the total zooplankton
population (see Appendix 2).
Patterns of Species Diversity
"Patterns of species diversity exist" (MacArthur, 1965,
510).
p.
"The simplest measure of species diversity is a count of the
number of species" (p. 511). "Local variations in the species diversity
of small uniform habitats can usually be predicted in terms of the
structure and productivity of the habitat" (p. 531). However, if
diversity was from an area of complex and often obscure relationships,
Figure 5. Abundance of Acartla clausi in
relation to the six sampling lines.
Vertical arrows extend between
confidence limits taken to be onehalf to double the sample abundance
estimate.
30
124°00'
100
50
A
300
250
200
150
100
50
B
4
50
25
C4
20
10
Nautica1 milest
C
2
0
tE1I]
50
02D1
Offshore
31
124°0O'
125°OO'
I
I
I
I
100
50
E5
E3
E2
E1
100
50
F5
F
F
Off Shore
F
32
it is often not subject to a neat simplification.
Species-diversity of a community is a resultant of at least
three interrelated determinants - - characteris tics of environment, time during which species have evolved niche differentiation in relation to one another, and characteristics of the
particular species which have evolved, to form communities
in that environment, especially characteristics of the
dominants which affect environmental conditions for subordinate species (Whittaker, 1965, p. 257-258).
The spatial patterns of species diversity in this study are shown
in Figure 7, in which the number of species ranges from five, found
in stations of A-i and C-i, to 25, found in station C-5. Species
diversity shows no clear relation to the variation of latitude but varies
with distance from the coast. In all sampling lines, copepod diversity
generally increased with distance from the shore, although at the most
offshore station in line D diversity was slightly less than at the next
inshore station. The stations with least species were near the coast
with numbers varying from 5 to 11
,
while at the offshore stations, the
number of species was at least 18. There are three possible
explanations for this kind of distribution of species diversity.
1) Near the coast, wave action and a large degree of turbulence
make the environment unstable. This limits the number of species
which have evolved to maintain themselves in this sort of living
environment, while in the more stable offshore environment, a larger
number of species thrive in the more uniform, less hostile environmental conditions.
2) The sampling depth changed with distance from shore. Along
33
000t
20
10
A2
A4
A
20
A1
10
B5
B4
B3
Bz
20
10
c
0
10
c
C
20
Nautic1al mi1e
20
10
D3
D2D1
Offshore
Figure 7. Species diversity of copepod population in relation to
the six sampling lines.
34
125°OOt
I
I
124°OO'
'
I
I
I
30
10
30
20
10
F
(
'.
Offshore
35
the stations numbered 1 and 2, samples were collected from the depth
of 50 to 170 meters, but farther offshore, the depth was increased to
270 meters.
Thus, more species could be obtained from this greater
sampling range and consequent greater volume of water filtered.
3) The pattern of few species with large number of individuals
associated with many species with few individual is characteristic of
most population structures (Odum, 1959). That is, rich population
usually contains a few species and a population which contains many
species is usually represented by low abundance. In the present study,
the copepod population was found higher inshore than offshore. Thus,
more species would be expected offshore than inshore.
Correlation. Analysis of Dominant Species
Correlation between dominant species will be tested by the
rank- correlation method. The rank- correlation coefficient (Spearrnan,
1904) is usually denoted by rs. The r for two species is given by:
rS
l-
62di2
N(N2-l)
where
di = Difference in rank of a sample in orderings based on the
abundance of the two species.
N = Size of sample.
That is, the total number of stations.
Like the product-moment correlation coefficient, r, the rank
36
correlation can range from -1 (complete discordance) to +1 (complete
concordance) (Snedecor and Cochran, 1967). It is also a pure number
without unit and dimension.
In addition to the four dominant species, fish eggs, copepod
nauplii, euphausiids, and Eucalanus bungii were also included in the
correlation analysis. These were included because they occurred in
large numbers at some stations (like fish eggs, found in stations of
B-4, E-4, and F-4), or because of their biological importance. Most
of the eight organisms were found at all stations, except that copepod
nauplii were not found in station A- 1 and F-2, Acartia clausi not at
station C-2, and Eucalanus bungii not at stations A- 1 and C- 1. Table
4 shows the ranking of 25 stations for each of these eight groups. The
rank-correlation coefficients between each pairing of the eight
organisms are given in Table 5.
For the sample size of 25, the significance level of r at five
percent and one percent are 0. 396 and 0. 505, respectively. Thus, at
the five percent level, the values of the r listed in Table 5 can be
divided into three categories: 1) The first consisted of 18 pairs
(Appendix 4), in which the value of r
was between +0. 396 and
-0. 396 (i. e., the null hypothesis that there was no relationship was
not rejected), 2) the second (Table 6) included seven pairs, where r
was greater than 0. 396, and 3) The remaining three pairs formed the
third category (Table 7), for which the value of r
was less than
Table 4. Ranking of 25 sampling stations, based on the abundance of each of the eight organisms.
Station
(1)
A-i
A-2
A-4
B-2
B-3
B-4
B-5
(2)
(3)
24.5
13
17
2
4
2
25
24
22
20
17.5
3
21
22
19.5
11.5
24
6
21
15
16
9
7
20
8
19.5
23
25
22
5
10
4
2
1
c-i
7
C-2
C-4
5
20
25
12
15
18
E-2
E-3
E-4
E-5
F-i
F-2
F-3
F-4
F-5
6
9
(7)
23
18
E-i
(6)
17
7
20
D-2
D-3
D-4
D-5
(5)
13
10
7
8
D- 1
(4)
23. 5
16
9
15
23
24
22
25
5
19
11
6
12
23. 5
16
8
1
4
14
17
(1) Euphausiid
(2) Fish eggs
10
9
18
12
19
4
22
11
14
17
5
20
16
14. 5
21
13.5
1
6. 5
24.5
25
24
10
18
19
23
4
15
20
4
16
13
5
24.5
1
17
14
3
20
22
8
11
3
12
19
2
7
16
14.5
6.5
18
12
2
6
10
5
2
13
21
4
15
3
1
3
23
15
18
21
17
14
16
11
24.5
21
13
6
9
1
8.5
16
4
11.5
20
copepod nauplii
20
23
10. 5
10
2
19
0. similis
12
9
13
12
8
16
5
17.5
13
8
14
6
(3)
(4)
19
21
14
13.5
24
8. 5
3
11
7
18
3
22
7
2
6
11
3
1
(8)
10
8
25
10. 5
(5) A. longiremis
(6) A. clausi
22
9
-
1
5
16
23
(7) P. minutus
(8) E. bungii
(j)
Table 5. The rank-correlation coefficients between each pairing of the eight organisms.
Euphausiids
(1)
0. similis
(2)
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
1
-0.421
-0.702
-0.317
0.247
-0.133
0.440
0.223
0.401
-0.446
0.215
0.016
0.257
0.027
0.530
-0.083
0.443
0.695
0.330
0.011
-0.014
1
-0.60i
0.466
Copepod
nauplii
A. longiremis
A. clausi
P. minutus
Fish eggs
E. bungii
(3)
(4)
(5)
(6)
(7)
(8)
1
1
1
0.341
1
1
0.077
-0.232
0.131
-0.113
0.001
1
Table 6. Category-2, which shows positive correlation and has a value
of r greater than 0. 396.
Paired species
Rank- correlation
coefficient
Oithona sirnilis-Pseudocalanus minutus
2) Oithona similis-Acartia clausi
3) Acartia longiremis-Pseudocalanus minutus
4) Fish eggs-Oithona similis
0.401
5) Acartia longiremis-Acartia clausi
6) Oithona similis-Copepod nauplii
7) Fish eggs-Copepod nauplii
0. 530
1)
0. 440
0. 443
0. 466
0.601
0. 695
Table 7. Category-3, negatively correlated group, having the
conditions for r $ less than -0. 396.
Paired species
1) Euphausiids-Copepod nauplii
2) Euphausiids-Fish eggs
3) Euphausiids- Oithona similis
Rank- correlation
coeffi c lent
-0. 702
-0.446
-0. 421
40
-0. 396.
Examination of coefficients in the se-cond category shows there
are two groups of mutually correlated species (see Figure 8):
1)
The species, found in the first positively correlated group
(group 1), were Oithona sirnilis, Acartia clausi, Acartia longiremis,
and Pseudocalanus minutus. These four species were found most
abundantly near the coastal region. That is perhaps why they are
positively correlated.
Z) The second positively associated group included copepod
nauplii, fish eggs and Oithon similis. Since there are no data available
on the ecology of copepod nauplii and fish eggs along the Oregon coast,
it is difficult to make a conclusion or suggestion for this group.
The significantly negative correlations are between the abundance
of euphausiid larvae and the abundance of Oithona similis, fish eggs,
and copepod nauplii. At those stations where euphausiid larvae occur-
red in high abundance, the other three organisms were in low numbers.
This could be related to the following possibility--the predator-prey
relation: The food of euphausiids can be roughly grouped into three
classes. That is, phytoplankton, zooplankton, and detritus materials.
The stomach contents of euphausiids in this present collection
revealed that some stomachs were empty and some contained a few
fragments of crustacean exoskeleton, but none of the identifiable
contents was found to be that of Oithona similis
Poriomareva (1954)
41
Table 8. List of species which comprised
category-2 and category-3.
Number
1
2
3
4
5
6
7
Species
Euphausiids
Oithona similis
Copepod nauplii
Acartia longiremis
Acartia clausi
Pseudocalanus minutus
Fish eggs
(4)
(7)
(3)
Figure 8. Correlation of species between category.-2 and
category-3. Solid lines indicate positive correlation
and dotted lines indicate negative correlation. Numbers
refer to species listed in Table 8.
42
described the way in which euphausiids feed on the copepods. Once
the copepod has been captured, it is held by the mouth parts and its
integument pierced. The juices are then sucked from the body of the
copepod leaving an empty husk.
The remains are rejected from the
food basket and only a small quantity of unidentifiable fragments of
the exoskeleton enter the stomach of the euphausiids. Her results
have been confirmed by observation on. Thysanoessa raschii and
Megariyctiphanes norvegica by Mauchline and Fisher (1969). Therefore,
the possibility of a predator-prey relationship between euphausiid
larvae and Oithona similis, or copepod nauplii cannot be disproved
until more work on the feeding of euphausiids in the Oregon coastal
waters has been done.
Table 9 shows the ranking of 25 stations, based on the numerical
value of temperature, salinity, and distance from shore. Rankcorrelation analysis (see Table 10) of those factors relative to the
four dominant species, total abundance of copepods and percentage
of copepod indicated that no significant relation was apparent except
one pair, Pseudocalanus minutus to distance from shore. The r for
this pair was -0. 453.
direction.
Therefore, their occurrence was in the opposite
43
Table 9. Ranking of 25 sampling stations by the total abundance of
copepod, percentage of copepod, temperature, salinity,
and distance from shore.
Station
A-i
A-2
A-4
B-2
B-3
B-4
B-5
C-i
0-2
0-4
(])
18
10
(2)
14
4.5
(3)
11
19
23
1
24
7
1
19
4
13
17
25
20
25
14
13
2
25
20
9.5
18
6
2
3
5
25
9
3
7
20
24
2
21
16
1
19
3
14
23
4.5
17
17
16
4
24
24
15
12
9
16
21
11
8
E-1
E-2
E-3
E-4
E-5
3
23
F-2
F-3
F-4
F-5
(5)
21
23
D-1
D-2
D-3
D-4
D-5
F-i
(4)
9.5
15
7
19
22
5
15
ii
1
23
22
6
8
6
21
12
19
18
13
(1) Total abundance of copepod
(2) Percentage of copepod
(3) Temperature
(4) Salinity
(5) Distance from shore
8.5
22
5
12
9
10
6
14
7
3
2
17
13
11
8
18
4
20
21
14
12
15
10
6
25
15
11
5
24
22
18
12
8
2
7
20
8.5
16
13
17
10
4
16
1
44
Table 10.
The rank-correlation coefficients of these four dominant
species, total abundance of copepod and percentage of
copepod relative to temperature, salinity, and distance from
shore.
(1)
(2)
(3)
(4)
(5)
(6)
0.285
-0.256
0.087
0.103
-0.191
0.255
Salinity
-0.033
0.326
-0. 165
-0. 345
0.055
-0. 114
Distance
from
shore
0. 141
-0, 453
-0. 295
-0. 007
0.018
-0. 201
Temperature
(1) 0. similis
(2) P. minutus
(3) A. clausi
(4) A. longiremis
(5) Total abundance of copepod
(6) Percentage of copepod
45
DISCUSSION
The total abundance of copepods differed greatly between inshore
and offshore stations. Greater abundance was found inshore, with the
number approximately two times that found offshore. This was
possibly related tothe distribtion of phytoplankton which Laurs
(1967)
noted to be more abundant near shore. During periods of upwelling,
higher standing stock of primary producers occurred inshore than
offshore, supporting a larger copepod population. When a
comparison was made between the spatial distribution of total
abundance and the four dominant species, it revealed that both had
peaks in those stations adjacent to the coast and decreased in a
seaward direction.
The four dominant species have been considered as neritic
species and often occur in considerable abundance in the neritic zone.
This appears to be the case in the southern Oregon coastal waters.
Species diversity during mid-August,
described by Hebard
(1964)
(1966)
1963
resembled that
for the coastal waters off Newport. Cross
used a diversity index dependent upon relative diversity and
showed that the species diversity off Newport was greatest inshore
during all seasons of the year, and that offshore waters were usually
characterized by one or two species making up a very large percentage
of the total population during the winter, spring and autumn months.
in my present study, the highest number of species was consistently
46
found in the offshore stations.
However, when comparing the inshore and offshore copepod
populations, severa. differences are readily apparent. The inshore
copepod population has 1) a higher average abundance, 2) a lower
number of species, 3) and the four dominant species occur in
relatively large numbers per cubic meter.
Cross (1964) considered Acartia danae and Centropages
abdominalis to be important species and possible indicators of
seasonal hydrographic changes. He thought that C. abdominalis,
absent from Oregon coastal waters during the winter months may
closely correlate with the presence of the northerly flow of Davidson
current. In the summer period, from April through September,
when a southerly current was developed, C. abdominalis reappeared.
Cross found that the occurrence of A. danae contrasted to that of C.
abdominalis. That is, A.danae was found in Oregon coastal waters
only from October through May. In the present study, no specimen of
A. danae was present and C. abdominalis was recorded only at three
stations, B-3, B-4 and D-2 and was in small numbers.
47
SUMMARY
1)
Plankton samples were collected during the cruise of U.S. Coast
Guard Cutter MODOC in mid-August of 1963. On the cruise
vertical hauls were made at 25 stations along six lines, extending
westward from the southern Oregon coast to about 83 kilometers
offshore.
2)
Forty-one species of adult copepod were identified, including
representatives of 26 genera and 17 families. The total abundance
averaged 550/rn3, a little lor than that found by Cross during
1962.
This was possibly related to some random variation
between times of sampling, to methods used in collecting plank-
ton, or to differences in environmental factors in different years.
3)
Higher population densities of copepods as a group were found
inshore than offshore. This distribution was largely determined
by the four dominant species. Rank-correlation analysis of those
four dominant species, total abundance of copepod, and percentage
of copepod relative to temperature, salinity and distance from
shore shows that no significant relationship was apparent except
one pair, Psuedocalanus minutus to distance from shore. They
occurred in opposite directions.
4)
The dominant species were Oithona similis, Psuedocalanus
minutus, Acartia clausi, and Acartia longiremis. These four
species often dominate the entire copepod population over the
25
sampling stations, where they accounted for approximately 81
percent of the total copepod abundance.
5)
The patterns of species diversity, in general, are a result of at
least three interrelated determinants: 1) characteristics of
environment, 2) time, and 3) characteristics of som important
(dominant) species. In all sampling lines, except D, copepod
diversity had a tendency to increase with distance from the coast.
That is, the lowest number of species was near the coast with
five to 11 species, while at offshore stations there were at least
18.
The reason for this could be mainly due to their environ-
rnents. Near the coast, the wave action and large degree of
turbulence probably limit the number of species which have
evolved an adaption to the near shore environment, while in the
more stable offshore environment, large numbers of species can
tolerate the environmental conditions.
6)
Results from the correlation analysis of the dominant species
suggest that the first positively correlated group included
Oithona similis, Pseudocalanus minutus, Acartia clausi, and
Acartia longiremis. These species were believed to be mainly
neritic species. The second positively correlated species consisted of fish eggs, copepod nauplii and 0. similis. Since there
sereno available data concerned with their ecology off Oregon
coast, it is difficult to come to an independent conclusion. The
third negatively correlated category included Oithona similis,
fish eggs, copepod nauplii, and euphausiids. When euphausiids
were in high abundance, the other three groups of organisms
were in low abundance. Alternatively, the reverse was true.
50
BIBLIOGRAPHY
Ackefors, H. 1965. On the zooplankton fauna at Asks. Ophelia
2 (2):269-280.
Berrill, N. J,
1966.
The life of the ocean. New York, McGraw-
Hill, Inc. 232 p.
Brodskii, K. A. 1950. Calanoida of the far eastern seas and po1r
basin of the U. S. S. R. Jerusalem, Israel program for scientific
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Cameron, R. E. 1957. Some factors influencing the distribution of
pelagic copepods in the Queen Charlotte Islands area. Journal
of the Fisheries Research Board of Canada 14:165-202.
Clarke, G. L.
1934. The role of the copepods in the economy of
the sea. Fifth Pacific Science Congress, Vancouver, B. C.,
A 5.5, p. 2017-202 1.
Cross, F. A.
1964. Seasonal and geographical distribution of pelagic
copepods in Oregon coastal waters. Master's thesis. Corvallis,
Oregon State University. 73 numb. leaves.
Davis, C. C. 1949. The pelagic copepoda of the northeastern Pacific
ocean.
University of Washington Publications in Biology 14:1-118.
Elton, C. 1927. Animal ecology. London, Sidgwick and Johnson,
Ltd. 209 p.
Frolander, H. F.
1962. Quantitative estimation of temporal variation of zooplankton off the coast of Washington and British
Columbia. Journal of the Fisheries Research Board of Canada
19(4):656-675.
Grice, G. D. 1961. Calanoid copepods from equatorial waters of the
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186: 171-246.
Hardy, Alister. 1965. The open sea, Part 1: The world of
plankton. Boston, Houghton Mifflin. 335 p.
Hebard, J. F.
1966. Distribution of euphausiacea and copepods
off Oregon in relation to ocanogra.phic conditions. Ph. D. thesis.
Corvallis, Oregon State University. 85 numb. leaves.
51
Jesperson, P. and F. S. Russell.
Fiches D'jdentification Du
Zooplancton. Charlottenlund Slot-Danemark, Conseil Permanent
International Pour L'exploration De La Mer, no. 1-49.
1960.
Laurs, R. M. 1967. Coastal upwelling and the ecology of lower trophic
levels. Ph. D. thesis. Corvallis, Oregon State University, 121
numb, leaves.
Lebour, M. V. 1918. The food of post-larval fish. Journal of the
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MacArthur, R. H. 1965. Patterns of species diversity. Biological
Review of the Cambridge Philosophical Society 40:511-533,
Marukawa, H. 1934. Some notes on marine and freshwater copepods
in relation to the fishery economy in Japan. Fifth Pacific Science
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Mauchline, J. and L. R. Fisher.
The biology of euphausiids.
Advances in Marine Biology, Vol. 7. Academic Press. 454 p.
1969.
Mori, T. 1937. The pelagic copepoda from the neighbouring water of
Japan. Tokyo, Yokendo Co.
150 p.
Newell, G. E. and R. C. Newell. 1963. Marine plankton. London,
Hutchinson Educational. 220 p.
Odurn, E. P. 1959. Fundamentals of ecology. Philadelphia, W. B.
Saunders Co. 546 p.
Winston.
1963.
152 p.
Ecology. New York, Holt, Rinehart and
Olson, J. B. 1963. The pelagic cyclopoid copepods of the coastal
waters of Oregon, California and lower California, Ph. D. thesis,
Los Angeles, University of California. 208 numb. leaves.
Owen, R. W., Jr.
1963. Northeast Pacific albacore oceanography
survey. U. 5. Fish and Wildlife Service, Special Science Report
Fisheries. No. 444. 35 p.
Park, T. S.
ocean.
527- 572,
1968. Calanoid copepods from the central north Pacific
U. S. Fish and Wildlife Service, Fishery Bulletin 66(3):
-
52
Ponomareva, L. A. 1954. Copepods as food of euphausiids of the sea
of Japan. Doklady Academia Nauk. S. S. S. R. 98:153-154.
Rose, M.
1933.
Copepods P1agiques. Paris, Paul Lechevalier.
374 p.
Snedecor, G. W. and W. G. cochran. 1967. Statistical methods.
The Iowa. State University Press. 593 p.
Spearman, C. 1904. The proof and measurement of association
between two things. The American Journal of Psychology 15(1):
72-101.
Whittaker, R. H. 1965. Dominance and diversity in land plant
communities. Science 147:250-260.
Wiebe, P. H. and W. R. Holland. 1968. Plankton patchiness:
Effects on repeated net tows. Limnology and Oceanography 13(2):
315-321.
APPENDICES
53
APPENDIX 1
Abundance of four dominant species at each station.
P.
A.
0.
A.
Station s imilis
longiremis
minutus
claus i
no.
(no. /m
(no. /m
(no. /m
(no. /m
26.5
67. 3
67.4
159. 2
A-i
A-2
16.5
36.7
154. 1
199. 0
A-4
13.3
29.0
8.5
10. 9
2.2
B-2
224.2
21.8
50. 1
244.3
B-3
35. 1
16.9
10. 9
B-4
181.4
3.6
93.1
19.4
B-S
256.4
715.9
101.6
154.8
158.4
233.5
C-i
1.6
13. 1
C-2
209.2
129.4
10. 1
72.6
C-4
118.5
14.5
24.2
320.0
365.7
150.2
32.7
D-1
D-2
77.6
12.2
16. 3
71.4
D-3
60.5
159.6
4.8
10.9
D-4
135.4
118.5
14.5
64.1
)
(1)
%
)
)
96. 3
89.0
70.6
94.5
78.9
72.2
89.8
64.4
93.6
62.4
91.5
89.5
56.2
67.9
D-5
E- 1
120. 9
293. 9
70. 1
842. 5
7. 3
143. 6
18. 1
32. 7
70. 4
96. 5
E-2
E-3
E-4
E-5
93.3
128.2
440.2
169.3
457.1
95.6
96.8
54.4
165.7
50.8
914.3
90.9
94.3
91.6
147.5
189.9
34.5
24.5
8.5
14.5
36.3
111.9
11.7
38.5
8.5
67.7
61.3
76.2
64.0
92.3
79.9
73.0
61.2
66.0
F-i
F-2
F-3
F-4
F-5
Average
82.2
270.9
177.6
194.1
(2) %
35.3
29. 0
19.4
18.7
9.3
2.4
12.1
9.7
29.0
21.8
28.7
5.0
2.4
31.6
5.7
(1) Percentages in total abundance of copepod, if four species
combined.
(2) Percentage of each dominant species in the total abundance of
copepod.
54
APPENDIX 2
Abundance of euphausiids, fish eggs, copepod nauplii, and Eucalanus
bungii.
Station
no.
A-i
A-2
A-4
B-2
B-3
B-4
B-5
c-i
C-2
C-4
D-1
D-2
D-3
D-4
D-5
E-1
E-2
E-3
E-4
E-5
F-i
F-2
F-3
F-4
F-5
Euphausiids
(no. /m3)
1.3
1.8
11.3
Fish
eggs
(no. /rn)
40.8
Copepod
nauplii
(no. /m)
-
Eucalanus
bungii
(no. /m)
-
117.4
14.5
25.7
6.1
0.20
0.80
10. 3
10. 9
6. 5
0. 54
0.5
0.8
0.6
5.3
45.9
0.50
319.3
30.2
66.5
914. 3
82. 3
17.9
6.5
0. 31
0. 60
-
8. 8
2. 4
2. 4
0. 60
0.4
2.2
41.1
6.5
0.90
0.61
0.64
71.4
26.1
59.5
25.4
94.8
39.2
6.1
137.9
81.0
61.7
39.2
15.2
60.5
350. 7
142. 7
1. 32
1.0
6.i
0.5
0.3
0.6
1.6
6.9
1.3
0.4
0.8
5.2
11.8
151.2
70.1
55.6
74,6
51.3
91.9
65.3
10. 3
1. 3
130. 6
1232. 5
53.2
0.76
2.92
11.66
1.74
145. 1
0. 57
0.8
67.7
96.8
0.04
-
1. 10
0.60
0.22
2.04
1. 16
3.02
Species of copepods other than four dominant species and their
abundance at each station.
Station
A-i
A-2
A.-4
B-2
B-3
B-4
B-5
(1)
0.22
1.72
0.45
1.22
0.07
0.03
0.53
(2)
(3)
(4)
(5)
(6)
(7)
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0.03
-
-
-
-
-
-
-
-
-
-
-
0. 11
0.03
-
-
0. 04
-
-
-
-
-
3. 62
-
-
0.17
0.08
c-i
-
-
C-2
C-4
3. 10
0. 45
0. 15
-
-
-
0. 04
0. 04
0. 03
0. 04
D-i
0.20
1.53
0.19
0.20
0.25
0.03
-
0.20
-
-
-
-
-
-
-
-
-
0.13
-
-
4.84
0. 26
0. 16
0. 03
0. 07
-
0. 03
0. 03
-
6. 05
-
-
-
0. 08
-
-
-
-
-
-
-
-
0.51
0.19
0.15
0.03
-
D-2
D-3
D-4
D-5
E-1
E-2
E-3
E-4
E-5
0. 11
-
F-i
0.30
0.58
0.15
0.29
F-2
0. 44
F-3
F-4
0.23
F-5
Frequency 21
-
-
-
-
-
-
-
-
-
-
-
-
0.08
-
-
12.09
-
-
-
-
-
-
-
-
-
-
0. 14
-
0. 07
2. 41
0.07
-
-
-
-
-
-
1.21
-
4.84
-
0. 11
-
-
-
-
-
0.03
-
-
16
2
(1) Calanus finmarchicus
(2) Calanus pacificus
(3) Calanus cristatus
(4) Eucalanus elongatus hyalinus
7
3
2
8
(5) Rhincalanus nasutus
(6) Clausocalanus arcuicornis
(7) Aetideus armatus
56
Appendix 3 (Continued).
Station
no.
(8)
(12)
(10)
(11)
-
0.08
0.15
-
-
-
-
-
-
-
-
-
0.03
0.07
0.07
-
-
-
-
-
0.30
-
-
0.03
-
-
(9)
(13)
A-i
A-2
A-4
B-2
B-3
B-4
B-5
C-i
C-2
C-4
0. 03
0.07
D-1
D- 2
D- 3
D- 4
-
D-5
-
0.11
0.07
0.04
E-1
E-2
E-3
E-4
E-5
-
-
-
-
0.08
0.11
-
-
-
F-i
F- 5
Frequency
0. 19
1
(8) Gaidius brevispinus
(9) Gaidius tenuispinus
(10) Gaidius pungens
-
0.03
0.03
0.18
-
F-2
F-3
F-4
0.19
0.30
1
0.07
0.04
-
-
-
-
-
-
-
0.07
-
-
-
0.11
-
-
0. 07
0. 22
0. 04
-
8
13
3
2
(11) Euchirella pulchra
(12) Euchirella curticauda
(13) Chirundina streetsi
57
Appendix 3 (Continued).
Station
no.
A-2
A-4
B-2
B-3
B-4
B-S
C-i
C-2
C-4
D-1
D-2
D-3
D-4
D-5
E-1
E-2
E-3
E-4
E-5
F-i
F-2
F-3
F-4
F-5
Frequency
(14)
(15)
(16)
(17)
(18)
(19)
-
-
0.05
-
-
-
0. 08
-
0. 03
0. 03
-
-
-
-
-
-
0.02
0.07
-
-
0. 18
-
-
0.23
-
-
-
-
0.03
-
-
-
-
-
0.03
-
-
-
-
-
-
-
-
-
-
0. 03
0. 04
0. 03
-
0. 03
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0. 03
0. 15
0. 03
0. 03
0. 03
-
-
-
-
0.03
0.03
0.11
0.23
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0.23
0.22
-
-
0. 03
-
-
-
-
-
-
-
-
-
2
(14) Undeuchaeta major
(15) Undeuchaeta plumosa
(16) Euchaeta japonica
-
-
-
0.03
-
-
-
-
0. 03
0. 04
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0.03
0.07
0.26
0.03
-
-
4
16
4
6
i
(17) Phaenna spinifera
(18) Scottocalanus persecans
(19) Lophothrix frontalis
Appendix 3 (Continued).
Station
no.
A-i
A-2
A-4
B-2
B-3
B-4
B-5
C-i
C-2
C-4
D-1
D-2
D-3
D-4
D-5
E-i
E-2
E-3
E-4
E-5
F-i
F-2
F-3
F-4
F-S
Frequency
(20)
(21)
(22)
(23)
(24)
(25)
-
-
-
-
-
-
-
7.28
0.05
0.05
-
-
-
-
0. 03
0. 11
0. 03
0. 03
-
-
-
-
-
-
-
0.03
-
-
-
7.86
3.63
-
-
-
-
-
4. 72
0.03
0. 03
-
-
-
-
-
-
-
-
-
0.07
-
-
-
-
-
0. 22
0. 03
0. 03
0. 03
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0.03
0.04
0.03
0.03
0.03
0. 04
-
9.75
19.35
-
-
0. 04
-
0. 16
-
-
-
-
-
-
-
75.80
-
-
-
-
-
-
0. 03
0. 03
0. 04
-
3.70
-
-
-
-
0. 38
0.03
-
0.07
-
-
-
-
-
-
-
-
0.07
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0. 03
0. 04
7
8
8
4
-
9. 70
-
0. 03
-
1
24. 18
14
(20) Scaphocalanus brevicornis
(21) Metridia lucens
(22) Pleuromamma abdominalis
(23) Pleuromamma xiphias
(24) Pleuromanima quadrungulata
(25) Pleuromamma scutullata
Appendix 3 (Continued).
Station
A-i
A-2
A-4
B-2
B-3
B-4
B-5
C-i
C-2
C-4
D-1
D-2
D-3
D-4
D-5
E-i
E-2
E-3
E-4
E-5
F-i
F-2
F-3
F-4
F-5
Frequency
(26)
(27)
(28)
(29)
(30)
(31)
-
-
-
-
-
-
-
-
-
-
-
0. 03
0. 08
0. 08
-
-
-
-
-
-
-
-
0.60
-
-
-
-
-
1.21
-
-
-
-
-
-
-
0.03
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0. 22
0. 18
0. ii
-
-
-
-
-
-
-
-
4.08
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0.03
0.03
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0.04
-
-
-
-
-
-
-
-
-
-
-
0. ii
0.08
0.03
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
0.08
-
-
0.03
3
2
8
3
1
1
(26) Centropages abdominalis
(27) Lucicutia flavicornis
(28) Heterorhabdus tanneri
(29) Heterostylites iongicornis
(30) Heterostylites major
(31) Candacia columbiae
Appendix 3 (Continued).
Station
no.
A-2
A-4
B-2
B-3
B-4
B-5
(35)
(36)
-
1.83
3.63
10.09
7.26
4.84
-
-
-
2. 17
26.00
31.44
24.19
3.02
-
-
29. 03
(32)
(33)
(34)
-
-
-
0.32
-
-
-
C-i
-
C-2
C-4
-
0.03
-
3.02
9.68
9.68
1.63
6.05
0. 03
-
-
9. 68
-
-
19.59
6.53
-
-
4.08
-
-
-
-
4.84
-
-
-
12.09
-
-
-
-
-
-
8.47
6.53
-
-
10.49
9. 33
D-1
D-2
D-3
D-4
D-5
E-1
E-2
E-3
E-4
E-5
F-i
F-2
F-3
F-4
F-5
Frequency
-
-
-
-
-
-
-
-
-
1.20
(37)
-
-
-
-
6.53
-
-
18.39
26.61
18.14
-
-
-
-
-
-
-
8.47
1 20
41.12
-
-
-
12. 09
24. 19
3. 68
-
-
-
2.42
24.19
-
-
-
-
-
-
-
-
-
6. 98
9. 33
-
-
-
3,63
18.66
9.68
-
-
-
9.67
16. 93
70. 14
-
-
-
-
4.84
50.79
-
2
1
5
21
18
6
(32) Candacia bipinnata
(33) Labidocera amphitrites
(34) Acartia tonsa
(35) Oithona spinirostris
(36) Oncaea conifera
(37) Corycaeus sp.
-
2.42
61
APPENDIX 4
The least associated group which had value of r between +0. 396
and -0. 396.
Paired species
Euphausiids-Acartia longiremis
2) Acartia longiremis-Eucalanus bungii
3) Euphausiids-Acartia clausi
4) Eucalanus bungii- Pseudocalanus minutus
5) Copepodnauplii-Pseudocalanus minutus
6) Fish eggs-Pseudocalanus minutus
7) Fish eggs-.Eucalanus bungii
8) Fish eggs-Acartia clausi
9) Oithoria similis-Eucalanus bungii
10) Copepod nauplii-Acartia clausi
11) Copepod nauplii-Eucalarius bungii
12) Acartia clausi-Eucalanus bungii
13) Euphausiids-Eucalanus bungii
14) Euphausiids- Pseudocalanus niinutus
15) Oithona similis-Acartia longiremis
16) Copepod nauplii-Acartia longiremis
17) Fish eggs-Acartia longiremis
18) Acartia clausi-Pseudocalanus minutus
1)
Rank-correlation
coefficient
-0. 317
-0. 232
-0. 133
-0. 113
-0.083
-0. 014
0. 001
0.011
0. 016
0. 027
0.077
0. 131
0.215
0. 223
0. 247
0. 257
0. 330
0.341
62
APPENDIX 5
Observed surface temperature, salinity and concentration of oxygen
at each station.
Concentration
Salinity
Temperature
Station
(°C)
(%
of oxygen
)
(mill)
5.82
A-i
9.77
33. 682
A-2
A-4
B-2
B-3
B-4
B-5
10. 15
33.345
32.232
6. 96
4. 55
C-i
9. 62
C-2
C-4
10.42
D-1
D-Z
D-3
D-4
D-5
11.14
9.91
12.04
33. 863
33. 781
33. 735
32. 163
33. 853
33. 799
33. 061
33. 701
E-i
E-2
E-3
E-4
E-5
F-i
F-2
F-3
F-4
F-5
15.24
9. 52
10.20
10. 73
13.33
10. 96
5,99
4.95
5. 83
6.76
4. 85
5.53
7. 07
33.772
33.465
6,63
5,05
6.57
12. 63
33. 125
8. 71
12.56
12.99
11.15
12.84
13.46
14.51
10.91
11.27
12.49
12.70
13.40
33.116
8.42
8 27
5.95
6,83
7.83
8.14
5,70
6.57
8.03
8.23
33. 612
33.658
33.565
33. 369
33. 110
33. 716
33.701
33. 634
33. 511
33. 546
8. 36